This article delves into the development of Japanese Chinese character variations, and how they fit into the broader study of Chinese characters. By examining the differences between early Japanese kanji and modern Japanese writing systems, as well as the varying approaches of Chinese and Japanese scholars in studying Japanese kanji, we can propose a more fitting classification and naming method better suited to studying Chinese characters. To that end, we take the Wamyō Ruiju Shō (倭名類聚抄) as an example, exhaustively sorting out the situation of variant characters in the manuscript across different eras, and referring to other ancient Chinese dictionaries from the same period. This article introduces concepts like “inherited variants” and “Japan saved variants” to make studying these characters more comprehensive.

Written in the Heian period, Shinsenjikyo was the first radical categorized ancient dictionary in Japan to overhaul the radicals of Han characters. Domestic scholars got new progress in various aspects of its research. However, they have neglected the radical research of Shinsenjikyo, and there was a lack of discussion on the source of its new radicals and the basis for transforming them. First, this article attempts to discuss the radical reform method of the book. Shinsenjikyo has made various transformations and adjustments to radicals, including changing the arrangement of radicals, adding new radicals, reducing the number of radicals, and readjusting the returned characters. Next, this article discusses the strengths and weaknesses of the Shinsenjikyo in the treatment of radicals. Through these discussions, we can see the differences between Chinese and Japanese ancient dictionaries and it will also help us have a clearer understanding of their relationships and characteristics.